A diet enriched in a polyunsaturated fatty acid, eicosapentaenoic acid, markedly retards the development of autoimmunity in (NZB x NZW) Fl females. This works even after the onset of disease. Human trials are being carried out. Cyclophosphamide is effective treatment in a variety of autoimmune strains unrelated to the cellular basis of illness or the nature (B or T cell) of the proliferating cells. This therapy is effective against the lymphadenopathy of MRL-lpr/lpr and C3H/HeJ-gld/gld mice and the coronary artery disease of BXSB and (NZW x BXSB)F1 mice as well as the renal disease of most examples of murine lupus. Cyclophosphamide markedly reduces the elevated myb RNA in MRL-lpr/lpr mice lymph nodes and increases the very low thymic myb expression. Cyclosporin A, a drug which interferes with T cell function, is effective treatment for the arthritis, nephritis, and lymphoproliferation of MRL-lpr/lpr mice.